1. Field of the Invention
The present invention relates to engage and disengage means and a photosensitive medium cleaning device of a liquid printer eliminating remaining filth in the photosensitive medium by contacting a cleaning roller with the photosensitive medium and separating the cleaning roller from the photosensitive medium using the engage and disengage means. The present invention is based on Korean Patent Application No. 2001-9572, which is incorporated herein by reference.
2. Description of the Related Art
Generally, printers such as a laser printer and a photocopying machine, are divided into two groups according to their developing method: one employing a dry method using powder toner and the other employing the wet method using blended liquid toner hydrocarbon solvents like NORPAR. The two methods develop a predetermined image by supplying toner to a photosensitive medium like a photosensitive belt, on which an electrostatic latent image is formed. Then, the developed image is printed on a paper as the paper goes through a transferring medium by contacting with the photosensitive belt. Recently, the wet method is widely applied.
FIG. 1 is a schematic block diagram showing a conventional printer employing a wet developing method.
As shown in FIG. 1, a printer employing a wet developing method includes: a photosensitive belt 10 supported by a supporting roller 11a, steering roller 11b, and a driving roller 11c; a plurality of laser scanning units (LSU) 13 for forming an electrostatic latent image on the photosensitive belt 10; a plurality of developing devices 14 for supplying a developing device with mixed toner containing predetermined colors and carrier on the electrostatic latent image formed on the photosensitive belt 10 and developing a predetermined image; a drying unit 15 for drying carrier that is left on the photosensitive belt 10 after going through the developing devices 14; a transferring unit 16 for transferring the developed image on the photosensitive belt 10 to the paper P; and a cleaning device 20 for cleansing the photosensitive belt 10.
The transferring unit 16 includes a transferring roller 17 receiving an image from the photosensitive belt 10 while rotating in contact with the photosensitive belt 10, and a settling roller 18 that rotates in contact with the transferring roller. A paper is printed on while moving between the settling roller 18 and the transferring roller 17 and receiving an image transferred from the transferring roller 17.
The cleaning device 20 is formed for eliminating filth such as dust or remaining toner on the photosensitive belt 10, which has not transferred to the transferring roller 17 from the photosensitive belt 10 during a printing operation. The cleaning device 20 includes a cleaning roller 21, which contacts with the photosensitive belt 10 and rotates, and a NORPAR supplying unit 23 for supplying liquid NORPAR to the cleaning roller 21. The cleaning roller 21 is disposed for rotating in contact with the photosensitive belt 10, and the cleaning roller 21 is selectively rotated by a driving source (not shown). The NORPAR supplying unit 23 wets the cleaning roller 21 with NORPAR supplied from a NORPAR tank 24 to the cleaning roller 21. Therefore, the cleaning roller 21, wet with NORPAR, rotates in contact with the photosensitive belt, and thus removes remaining toner or filth from the photosensitive belt 10.
However, in a conventional cleaning device 20 with the above construction, the cleaning roller 21 is maintained in contact all the time with the photosensitive belt 10. Therefore, even when printing is not performed, the photosensitive belt 10 and the cleaning roller 21 are contacted with each other, and NORPAR on the cleaning roller 21 penetrates to the photosensitive belt 10. Then, the photosensitive belt 10 swells because of the penetrated NORPAR, and when printing is performed, the image is not developed as a normal one and the life span of the photosensitive belt 10 is shortened.
The present invention has been made to overcome the above-mentioned problems of the related art. Accordingly, it is an object of the present invention to provide engage and disengage means having an improved construction for engaging and disengaging an object to one side and a photosensitive medium cleaning device of a printer employing the wet method using the engage and disengage means.
To accomplish the above object, an embodiment of the present invention, including an engage and disengage means for engaging and disengaging an object to one direction, comprises: a housing; a driving motor disposed at the housing; a rotating bracket, rotatably disposed at the housing, for supporting the object; a cam unit, capable of rotating and moving straight by a rotating force of the driving motor, for transferring the rotating bracket to one side by being rotated after being moved straight to the rotating bracket while the driving unit is rotating in one direction, so that the rotating bracket can return to its initial position by being separated from the rotating bracket while the driving motor is rotating in the opposite direction.
It is preferable that the cam unit comprises: a driving shaft disposed at the housing for rotating by the driving motor; a cylinder type pipe disposed at the circumference of the driving shaft for rotating and moving straight for a predetermined length, and while the pipe is moving straight in one direction from its initial position, the front end of the pipe contacts with the rotating bracket and separates from the rotating bracket; a power transferring unit that transfers the rotating of the driving shaft to straight movement of the pipe, so that the pipe can move straight in one direction, and when the pipe is contacted with the rotating bracket, transfers the entire rotating power to the pipe for rotating; and a guide unit for guiding the rotating bracket to mount on the circumference of the pipe and rotate, while the pipe is rotating in one direction being contacted with the rotating bracket, and guiding the rotating bracket to return to its initial position, while the pipe is rotating in the opposite direction.
The photosensitive medium cleaning device of a printer employing the wet method according to the present invention, comprises: a cleaning roller for eliminating filth on the surface of the photosensitive medium by contacting with the photosensitive medium; a NORPAR supplying unit for supplying liquid NORPAR to the cleaning roller; and engage and disengage means for rotatably supporting the cleaning roller, and contacting the cleaning roller with the photosensitive medium and separating the cleaning roller from the photosensitive medium.
The photosensitive medium cleaning device of a printer employing the wet method according to the present invention, comprises: a cleaning roller for eliminating filth on the surface of the photosensitive medium by contacting with the photosensitive medium; a norpar supplying unit for supplying liquid norpar to the cleaning roller; and engage and disengage means for rotatably supporting the cleaning roller, and contacting the cleaning roller with the photosensitive medium and separating the cleaning roller from the photosensitive medium.
It is advisable that the engage and disengage means includes: a housing fixed closely to the photosensitive medium; a driving motor disposed at the housing for rotating a cleaning roller contacted with the photosensitive medium; a rotating bracket rotatably disposed at the housing for rotatably supporting the cleaning roller and contacting the cleaning roller with the photosensitive medium and separating the cleaning roller from the photosensitive medium; and a cam unit, rotating and moving straight by a rotating force of the driving motor, moves the rotating bracket for the cleaning roller to be contacted with the photosensitive medium by being rotated after being moved to the rotating bracket, while the driving motor is rotating in one direction, and returns the rotating bracket to its initial position by being separated from the rotating bracket, while the rotating motor is rotating in the opposite direction.
It is preferable that the cam unit includes: a driving shaft disposed at the housing for being rotated by the driving motor; a cylinder type pipe disposed at the circumference of the driving shaft for rotating and moving straight, and while the pipe is moving straight in one direction from its initial position, the front end of the pipe contacts with the rotating bracket; a power transferring unit for transferring the rotating of the driving shaft into straight movement of the pipe, so that the pipe can move straight in one direction, and when the pipe is contacted with the rotating bracket, transfers the rotating force to the pipe; and a guide unit for guiding the rotating bracket to mount on the circumference of the pipe when the pipe is contacted with the rotating bracket and rotate in one direction, and guiding the rotating bracket to get down form the circumference of the pipe while the pipe is rotating in the opposite direction.
It is recommended that the power transferring unit includes: a spiral guide slit formed at the pipe for a predetermined length; a guide pin fixed at the circumference of the driving shaft for guiding movement of the pipe as the guide pin relatively moves following the guide slit while the driving unit is rotating; and a friction member for supplying a friction force to the pipe. The friction member supplies a friction force to the pipe and prevents the pipe from being rotated by rotating power of the driving shaft, so that the pipe can move straight by the relative movement of the guide pin and the guide slit.
It is advisable that the guide slit, formed diagonally with an angle of more than 45 degrees to the driving shaft, guides the guide pin to relatively slide following the guide slit with less force than the friction force of the friction member.
It is preferable that the photosensitive medium cleaning device of a printer employing the wet method further includes a spring member for flexibly pressing the pipe in the direction of separating from the rotating bracket.
It is recommended that the guide unit includes a contacting member protruding from the rotating bracket to the range of straight movement of the pipe and a stopping member formed at a diagonal surface on one end side of the pipe at a predetermined angle along the direction of the circumference. While the pipe is rotating after being moved to the contacting member, the contacting member moves following the diagonal surface, is stopped by the stopping member, and mounts on the circumference of the pipe so that the cleaning roller can contact with the photosensitive medium.
It is preferable that the photosensitive medium cleaning device of a printer employing the wet method further includes a spring for supplying a flexible force for the pipe to return to its initial position when the driving shaft stops. The rotating bracket, disposed eccentrically from a rotating center, is rotated by its own weight so that the cleaning roller can be separated from the photosensitive medium when the cleaning roller, contacted with the photosensitive medium, is separated from the pipe.
It is recommended that the photosensitive medium cleaning device of a printer employing the wet method further includes a spring member for flexibly pressing the rotating bracket in the direction of the cleaning roller until separated from the photosensitive medium.
It is advisable that the NORPAR supplying unit includes: a discharging nozzle having a plurality of nozzles disposed at the rotating bracket to the opposite side of the cleaning roller for discharging NORPAR; a NORPAR tank for storing NORPAR and supplying NORPAR to the discharging nozzle; and a supplying pump for pumping the NORPAR in the NORPAR tank to the discharging nozzle through a supplying passage.
It is preferable that the cleaning roller is disposed at a predetermined place for being contacted with the photosensitive medium before an electrostatic latent image being formed thereon by a light projected from a laser projecting unit.